Deep drawing of cylindrical shapes



Sept- 1, 1959 M. A. LAVIGNE DEEP DRAWING oF CYLINDRICAL sHAPEs 4Sheets-Sheet l Filed NOV. 28, 1956 Ina 2,1220 Alm/ma' mf/@wf M. A.LAVIGNE 4 sheets-sheet 2 Sept. 1, 1959 DEEP DRAWING 0F CYLINDRICALSHAPES Filed Nov. 28, 1956 sptl, 1959 i M. A. L AvlGNE 2,901,995

DEEP DRAWING OF' CYLINDRICAL SHAPES i` 410 iov 40@ j2me/rfa# /W/c//Afl,4.1 Hwa/VE Sept. l, 1959 M. A. LAVIGNE DEEP DRAWING oF CYLINDRICALsHAPEs 4 Sheets-Sheet 4 Filed Nov. 28, 1956 United States Patent DEEPDRAWING F CYLINDRICAL SHAPES Michael A. Lavigne, Verdun, Quebec, Canada,assignmof twenty-five percent to Jacob Truax, St. Dorothee, Quebec,Canada Application November 28, "1956, Serial No. 624,783

9 Claims. (Cl. 1'13-38) The invention is concerned with an improvedmethod of deep drawing cylindrical shapes from a at blank.

A single step deep drawing of blanks from sheet metal or metal foil hasbeen the aim of considerable prior art research in tool design.

Various attempts have been made involving the use of various types ofblank trapping rings and special means of lubrication to accomplish thepurpose of forming, in one continuous step and from a flat blank, acylindrical shape preferably having a closed end.

This desired result has not been achieved as far as is known to ltheapplicant without involving multiple stage heat treatments and step byst ep dies.

The, present invention provides a means of accomplishing one stepforming from a flat blank into a cylindrical shape.

ln accordance with the invention, this is accomplished by a formingpunch and die arrangement which includes a die having a centrallylocated spring biased work-supporting mandrel, and a forming punchshaped to correspond with the die cavity, and having a spring loadedpressure ring surrounding the punch for the purpose of retaining thematerial as it is drawn within the die. A main feature of the presentstructure is in the provision of an encircling pressure applying member,which cooperates with the forming punch and is located about the topperiphery of the die cavity, so as to surround and be adapted tocontinuously work the material as it is drawn into the die by thedownward progress of the punch. This pressure applying member, in onepreferred construction, comprises of a plurality of resiliently biasedpistons or hammers which are mounted radially about the die cavity andare adapted, by mechanical means, to be reciprocated toward the centralaxis of the die and against the material being drawn down into the dieby the punch.

Motion transmitting means, preferably in the form of a rack and geararrangement, are adapted to transmit the stroke or forming motion of thepunch relative to the dierinto a. driving motion to the pressureapplying pistons. This is accomplished in one preferred form by having aplanetary type gear mounted on the die so as to surround the die cavityand driven through a pinion gear. 'Ilhe pinion gear in turn is driven bya toothed rack extending between the punch and die. With thisarrangement, the forming movement of the punch towards the die drivesthe rack against the pinion, and rotation of the pinion, through thebevel gear, turns the planetary gear. The inside surface of theplanetary gear is provided with a plurality of circumferentially spacedapart cams or cam teeth which are adapted to come into actuating contactwith the ends of the pressure punches, continuously andin sequence.

The innerendslof these reciprocating punches impart a. pulsatingpressure or hammering actionagainst the surface vof the materialV as itis being drawn into the die ,caYi. This pulsating action is in stepsequence with theforming action of the punch. relative to the die and2,901,995 Patented Sept. 1, 1959 lCC is controlled, by the mechanicaldrive, so that the material which is being formed is alternatively heldand released as it is being drawn into shape, or in other words is beingWorked as it is being drawn, so as -to maintain the wall thickness ofthe shape being formed While permitting the drawing of the material intothe desired cylindrical outline. This action may be broadly described asbeing analagous to the eiect applied to a metal blank when it is spunonto a forming mandrel in standard metal spinning processes.

Having thus generally described the nature of the invention, particularreference will be made to the accompanying drawings, wherein there isshown by Way of illustration a forming punch and die embodying thefeatures mentioned above, and in which:

Figure l is a view in front elevation of a punch and die arrangementadapted to carry out the forming method of the invention;

Figure 2 is a plan View partially in cross-section of the dieconstruction shown in Figure l along the line 2--2 to illustrate therelative position and arrangement of the driving gears and the radialspoke-like pressure applying members;

Figure 3 is an enlarged cross-sectional view of Figure 2 along the line3 3 to show the individual pressure applying members in more detail;

Figure 4 is a cross-sectional view of Figure 2 along the line 4 4 toshow the rack and pinion drive in more detail;

Figure 5 is a longitudinal View of the construct-ion shown in Figure l,partially in section, to illustrate the relative position of the punch,the material restraining draw ring, the die and cooperating die mandrel,and the pressure applying members with :the driving means;

Figure 6 is a view corresponding to Figure 5 with the punch shown in theterminal position of the forming stroke.

With particular reference to Figures l and 5 of the drawings, the punchand die apparatus of the invention is shown as being mounted on asuitable die set having a base portion 1l) and a top portion 12. Themovement of the top portion 12 relative to the base portion 10 is guidedin the usual manner by die standards 14 which are secured to the base 10and extend through suitable bearings provided in the top 12.

The forming punch of the apparatus is indicated at Ztl. This is attachedto the top portion 12 of the die set by suitable machine bolts 22, thecentral lower face of the die set portion 12 being relieved toaccommodate the upper end of the punch. The top portion 12 of the dieset is provided with the usual shaft or shank 18 for attachment to theram of the punch press. The shank 18 is centrally disposed and is inaxial alignment with the punch 20.

A draw or pressure ring 30 is provided and is mounted on supportingshafts 32 which slidably pass through the top die set portion 12, shownmost clearly in Figure 5. Resilient springs 34 surround each shaft 32 sothat the pressure ring 30 is normally urged into alignment with thebottom or lowest extremity of the punch 20 so that it will be the firstportion of the punch arrangement to come into contact with the blank tobe drawn, thereby to resiliently retain it against the drawing orpulling motion of the punch.

The main die body into which the punch 20 is adapted to draw thematerial being formed is indicated at 40. This die body 40 is mounted tothe die set base 10 with the die cavity 42 in axial alignment with thepunch 20. The die body 40 is provided with a cylindrical extension 44which lits directly beneath the die body 40 and acts to support a diemandrel 46 in axial alignment with the die cavity 42. The extension 44is of hollow cylindrical formation and ts Within a central opening 11 inthe die set base 10. The mandrel 46 is mounted concentrically within theextension 44 with the lower end portion 47 iitting in and adapted toslidably move through and out of the lower end portion 45 of theextension 44 under the pressure of the punch 20. A coil spring 4S actsagainst an adjustable bushing 56 so as to normally maintain the mandrel46 within the die cavity 42 with the top surface flush with the topsurface of the die body 40.

The upper surface of the die body 4d is suitably recessed to provide amaterial receiving cavity 52 adapted to receive a blank of the desiredsize and contour for the drawing operation. This recess 52 correspondssubstantially to the outline of the draw ring 3i) so that when the drawring 30 engages with the blank or material, the material is held betweenthe upper surface of the die body 40 in the recess 52 and the lowersurface of the draw ring 30 where it is resiliently restrained by theaction of the coil springs 34 on the draw ring supporting arrangement.

In accordance With the present invention, the upper portion of the diebody 40 surrounding the die cavity 42 directly beneath the blanklocating recess 52 is bored to provide a plurality of radially extendingrecesses 60. Each of the recesses 60 has a first major portion 62 ofconstant diameter and a further portion 64, adjacent the outer peripheryof the die body, of greater diameter so as to provide a shoulder 65therebetween. A two-piece pressure piston or hammer 79 is mounted Withineach of the recesses 60, so that the inner ends '73 form an alignedencircling ring about the inner surface of the upper end of the diecavity 42. Each of the piston members 70 comprises of a iirst portion 72having the shaped end 73 which is adapted to engage directly with thematerial, and a slidably connected second portion 74, the end 75 ofwhich extends beyond the outer periphery of the die body 40 at thispoint and is adapted to be engaged for reciprocal movement as will bedescribed later.

As shown most clearly in Figure 3, each piston portion 72 includes anaxial recess 80 wherein a reduced diameter extension 84 of the portion74 slidably ts. A lost motion connection is made between the mating endsof the portions 84 and 72 by a slot and pin arrangement indicated at 86.A coil spring 38 surrounds the portion 84 and is adapted to resilientlyact between the interconnected piston portions 72 and 74. The outer end75 of each portion 74 is provided with an upstanding ange 9U which isadapted to slidably fit within the enlarged diameter portion 64 of thebore 60. By the threading engagement of an annular nut 92 within thecorresponding tapped end 94 of each of the bores 60 the piston members7) are each retained within the die body for restricted slidingmovement. A further coil spring 96 is provided which acts between theflange 9() and the shoulder 65 of the recess 60 so as to withdraw theinner ends 73 of the member 7 0 after each stroke.

In order to impart the desired reciprocal motion to each of the pressureapplying pistons 70, a planetary type gear 100 is mounted on the upperface of the die body 46 so as to concentrically surround the die cavity42 and be capable of driven rotation about the ends 7S of the pressurepistons 70. The inner face '102 of the gear 100 is provided with aplurality of circumferentially spaced apart cam surfaces or teeth 164which, upon rotation of the gear 100, are adapted to act against theprotruding ends of the pressure member 76 urging them in sequencetowards the centre of the die cavity. The outer periphery of the gear100 is provided with suitable teet 106 in the form of a bevel gear. Theteeth 1% of the gear 100 are in meshed engagement with the teeth of apinion gear 108 mounted on a shaft 11@ journalled for rotation on anextension 41 of the die body 46. A driving pinion gear 112 is alsomounted on the shaft 11i) and is in meshed engagement with an elongateddriving rack 114. The driving rack 114 has its upper end secured to 4the top portion 12 of the die set with the bottom end being supportedfor sliding movement through the eX- tension 41 of the die body 40, asshown in Figure 4.

With this arrangement, descent of the upper portion of the die set 12first brings the pressure ring 30 into engagement with a blank ofmaterial supported on the recess 52 of the die body 4t). The continueddescent of the punch 20 presses the centre portion ofthe materialagainst the upper face of the die mandrel 46 so that the material is nowfirmly trapped between the upper face of the mandrel 46 and the bottomof the punch 20 while being resiliently restrained about the outerperiphery by the pressure ring Sii. As the punch 20 descends it drawsthe material into the die cavity 42, while the pressure pistonarrangement described causes the pressure pistons 70 to rapidlyreciprocate in turn against the material, working it against the outerface of the punch 20.

Suction or vacuum pressure is also applied to the interior surface ofthe blank as it is engaged and drawn into the die through a plurality ofcircumferentially spaced apart openings 23 provided in the punch 20adjacent the lower end and also through the openings 21 in a perforatedplate 25 provided in the lower face of the punch 20. The punch 20 isrecessed inwardly from the lower face to provide a cylindrical airchamber 31 with the perforated plate 25 closing oi the open face of thischamber across the bottom of the punch. An axial boring 27 leadingthrough the punch connects with the chamber 31 and a source of vacuumand air pressure is connected to the top end 29 of the boring 27 througha suitable conduit means, not illustrated. A. known type of valvearrangement, not illustrated, is used to control the suction or vacuumpressure applied in sequence with air pressure so that on the down orforming stroke of the punch suction is applied through the openings 23,21 and maintained until the latter portion of the up stroke when thevacuum pressure is cut oit and air pressure applied.

It will be appreciated that due to the tapering shape of the punch 20the initial forming strokes of the pressure plunger 7d will be greaterthan when the punch 20 is near to or at the end of its stroke. Thisvariation in stroke is compensated for by the two-piece construction ofthe individual piston members 70, the springs 88 taking up thedilierence in stroke as the plunger portion 70 is telescoped towards theplunger portion 74. As the punch 20 continues to descend the surplusmaterial created by the graduated reduction in diameter is beingconstantly worked about the circumference of the punch so as to free itfor iiowing under the drawing action, avoiding the usual excessivereduction in Wall thickness as is normally caused by a single stepstraight draw in draw types dies.

vWhen the drawing operation is complete, as shown in Figure 6, theraising of the punch 20 permits the mandrel 46 to follow the punchupwards through the die cavity 42 while the pressure plungers 70 againact to work on or smooth out the outer surface of the drawn article asit is being withdrawn. When the punch is withdrawn to the position shownin Figure 1 the article is ejected from the punch by the air pressuresupplied through the openings 23, 21 in the punch body.

I claim:

1. An apparatus adapted for deep drawing of cylindrical shapes from flatblanks, comprising a forming punch and a die block having a formingcavity mounted in registered alignment for reciprocal movement relativeto each other, a resiliently biased draw ring mounted adjacent to andsurrounding said punch, means to actuate said punch, pressure actuatedmaterial working means mounted on said die about said die cavity andincluding portions extending Within said die cavity adapted to exertpulsating forming pressure to the material of a blank drawn into saiddie cavity by said forming punch, and driving means adapted to actuatesaid material working means in progressive sequence With the formingmotion of. Said punch relative to said die cavity, said pressureactuated material working means including a plurality ofcircumferentially spaced pressure pistons extending radially outwardsfrom said die cavity, one end of each of said pistons being located atthe inner surface of said die cavity with the other end extending beyondthe surface of said die block at that point, said driving means including a planetary gear mounted for rotation on said die block surroundingsaid pressure piston extended ends and having an internal surfaceprovided with spaced cam projections adapted to contact said pressurepiston ends in sequence on rotation of said gear, and cooperating rackand gear means mounted on said punch and die adapted to drive saidplanetary gear.

2. An apparatus, as claimed in claim 1, including a resiliently biasedsupporting mandrel mounted for sliding movement co-axially of said diecavity and having a top surface normally in register with the upperperipheral edge of said die cavity.

3. A11-apparatus, as claimed in claim l, wherein said punch is providedwith a plurality of spaced openings leading inwardly from the externalsurface of said punch adjacent the free end thereof and an axial boreconstituting a main fluid passage connected with said openings saidpunch iluid passage being adapted for connection to source of fluidpressure whereby said fluid pressure may be applied to the interior of ablank supported on said punch.

4. An apparatus adapted for deep drawing of cylindrical shapes from flatblanks, comprising a forming punch having an external contourcorresponding to the contour of the article to be formed, a forming dieblock having an internal die cavity corresponding in shape to theexternal contour of said punch, said forming punch being mounted inaxial register with said die block cavity for reciprocal engagementtherein, a resiliently biased draw ring mounted adjacent to andencircling said punch adapted to engage the surface of said die blocksurrounding said cavity, means to actuate said punch towards and awayfrom said die block a resiliently biased mandrel mounted for slidingmovement co-axially of said die cavity and having a top surface normallyin register with the upper peripheral edge of said die cavity, aplurality of circumferentially spaced pressure pistons mounted forsliding movement in said die block and extending radially outwards fromsaid die cavity, one end of each of said pistons extending within saiddie cavity with the other end extending 4beyond the outer surface ofsaid die block at that point, and driving means adapted to engage saidpistons extended ends and actuate said pistons other ends inwardlytowards the axis of said die cavity in progressive sequence with theforming movement of said punch relative to said die.

5. An apparatus, as claimed in claim 4, wherein said pistons eachcomprise two telescopically interconnected portions and spring means areprovided between said portions to resiliently maintain said portions inextended position.

6. An apparatus, as claimed in claim 4, wherein said -driving meanscomprises a planetary gear mounted on said die block spaced from andconcentric with said die cavity and encircling said pressure pistonsextended ends, each of said pistons having two telescopicallyinterconnected portions and spring means provided between said portionsto resiliently maintain said piston end portions in extended position,said planetary gear having a toothed external surface, an internalsurface provided with regularly spaced cam projections adapted tocontact said pressure piston ends in sequence upon rotation of saidgear, a bevel gear in meshed engagement with the external teeth of saidplanetary gear, said bevel gear being mounted for rotation on a commonshaft with a pinion gear, and a toothed rack in meshed engagement withsaid pinion gear, said rack being mounted between said punch and die andadapted for travel with said punch during its reciprocal movementrelative to said die.

7. An apparatus, as claimed in claim 4, wherein said punch is providedwith a plurality of spaced openings leading inwardly from the externalsurface of said punch adjacent the free end thereof and an axial boreconstituting a main fluid passage connected with said openings, saidpunch iluid passage being adapted for connection to a source of fluidpressure, whereby fluid pressure may be applied to the interior of ablank supported on said punch.

S. A method of accomplishing one stroke deep drawing of a flat one-pieceblank of deformable material into a hollow cylindrical shape,comprising, progressively applying forming pressure to the centreportion of said blank while resiliently restraining the portions of saidblank surrounding said centre portion so as to draw the material of saidblank evenly and progressively between spaced concentric parallel innerand outer forming surfaces of cylindrical formation, and in sequencewith said application of forming pressure continuously applying externalpulsating material working pressure on an annular portion of said blankmaterial and against said inner cylindrical forming surface as saidmaterial is drawn -between said inner `and outer forming surfaces,reversing said forming pressure to withdraw said formed blank on saidinner forming surface from engagement with said outer forming surface,and iinally removing said formed blank from said inner forming surface.

9. A method of accomplishing one stroke deep drawing, as claimed inclaim 8, including the step of applying suction pressure through saidinner supporting surface to the inner face of said blank during saiddrawing operation.

References Cited in the file of this patent UNITED STATES PATENTS935,791 Jenkins Oct. 5, 1909 1,265,901 Gabriel Mar. 14, 1918 2,393,131Vang Ian. 14, 1946 2,415,925 Wiley Feb. 18, 1947 2,658,549 Peachy Nov.l0, 1953

